A team including NE CASC researchers Ridwan Siddique, Ambarish Karmalkar, and Richard Palmer has published an article, "Hydrological Extremes across the Commonwealth of Massachusetts in a Changing Climate," in The Journal of Hydrology: Regional Studies. The primary goal of this study is to assess the changes in future flood and drought conditions across watersheds in Massachusetts.
The Commonwealth of Massachusetts is projected to experience significant impacts from future climate change, including increases in extreme precipitation, flooding, and droughts. This study investigates the potential impacts of climate change and uncertainties on future floods and low flow conditions in the state's rivers and streams. Fourteen downscaled Global Circulation Model (GCM) projections under two greenhouse gas concentration pathways (RCP4.5 and RCP8.5) are used as inputs into a distributed hydrological model to obtain future streamflow conditions.
Even though Massachusetts has witnessed numerous extreme hydrological events in recent decades, few statewide studies provide projections of riverine floods and droughts generated by high-resolution, physically-based hydrological models and multiple climate change projections. Several parts of Massachusetts have recently experienced major floods, particularly during the years of 2006, 2009 and 2011. Similarly, substantial droughts have occurred during the years of 1985, 2002 and 2016. Many of these extreme events are not fully understood due to lack of statewide detailed analysis and comprehensive data.
Employing high-resolution climate projections and hydrological models is therefore crucial to effectively characterize current and future hydrological extremes across Massachusetts. By implementing a high-resolution distributed model, this study ensures a more detailed representation of topographical features and climate forcing as opposed to many other coarse-resolution macro scale modeling studies that were performed on the area in the past. This project examines 86 small- and medium-sized river basins. By modeling such a large number of sites within a relatively small area like Massachusetts, the researchers obtain a detailed portrayal of spatial and temporal trends for droughts and floods.
Ultimately, the study provides a range of new hydrological insights for the state of Massachusetts. Seasonal change projections of 100-year flood and a measure of drought are estimated through the near-term (years 2021−2060) and the far-term (years 2060−2099) relative to the base period (years 1981–2016). The median estimates of 100-year flood during winter report a 15 % or higher increases in many watersheds at the far-term. In contrast, flood magnitudes in spring show decreases for most of the watersheds during both near- and far-term. For seven-day, ten-year low flow estimates, the largest decreases are projected during the fall, and this trend is found to be consistent across future time periods.